The use of sound as a means of presenting computer-based services previously represented in visual form (e.g. on a computer monitor) has been proposed. In particular, it has been proposed that spatialisation processing of different sounds be performed such that the sounds, when played through loudspeakers or some other audio transducer, are presented at particular positions in the three-dimensional audio field. It is envisaged that this will enable Internet-style browsing using only sound-based links to services.
Such a three-dimensional audio interface will use spatialisation processing of sounds to present services in a synthetic, but realistically plotted, three-dimensional audio field. Sounds, representing services and/or information could be placed at different distances to the front, rear, left, right, up and down of the user. An example of a service is a restaurant. A pointer to the restaurant (the equivalent of a hyperlink) can be positioned in the audio field for subsequent selection. There are several ways in which the ‘audio hyperlink’ can be represented, for example by repeating a service name (e.g. the name of the restaurant) perhaps with a short description of the service, by using an earcon for the service (e.g. a memorable jingle or noise), or perhaps by using an audio feed from the service.
Such a system relies upon a high quality audio interface which is capable of rendering a three-dimensional audio field. Given that each sound, representing a service, is likely to be sent to a user's terminal from a remote device (e.g. the service provider's own computer) it follows that a data link is required. Where the data link has limited bandwidth, and is susceptible to interference and noise (for example, if a wireless telephony link is used) or if the channel employs lossy audio codecs (coder-decoders), it is likely that the link will degrade the three-dimensional nature of the audio. This may have the effect of masking any user-perception of three-dimensional positioning of sounds. This problem can be reduced if each audio component, i.e. each set of data relating to a particular sound, is transmitted independently to the user's terminal where the components are then combined to form the spatialisation processed data. This processed data is not subjected to the lossy transmission link. However, such a system will require larger overall bandwidth in order to carry the multiple audio components. In many network applications, particularly mobile wireless networks, the bandwidth of the access link or channel is a limited and expensive commodity.